(1) An affidavit sworn before—
(a) a party;
(b) a partner in a firm which is a party; or
(c) an employee of a party—
shall not be used in evidence by or on behalf of the party.
(2) Paragraph (1) shall not apply where the Crown is the party on whose behalf the affidavit is to be used and the affidavit is sworn before an employee of the Crown.